The vibration-dissociation kinetics of CO2/N2 mixture is studied using three different models: 1) state-to-state approach, 2) quasi-stationary and 3) step-ladder approximations. Numerical simulations are aimed to describe the results of experimental findings in mixtures 2000 ppm CO2 and 2000 ppm CO2%N2 at Teq=2326-2855 K and Peq=0.75-2.59 bar. The yield of O-atoms from the dissociating CO2 is calculated in quasi-stationary and in step-ladder approximations and compared with the experimental one measured by ARAS technique during ∼100 μs. The most interesting results are obtained at the early stage of vibrational intermode exchange in CO2 by means of state-to-state approach. The vibrational exchange of highly excited states (HES) of CO2 and N2 is studied on the base of step-ladder solution.